I did have one that bounced this year that was on extension.  It was still lingering as a rejection in the EF center but I just went back into the return for the heck of it.  The return e-file boxes were not checked.  However, once I "unchecked" the extension e-file box, the rejection disappeared.  Out of curiosity, I went back in to click the extension e-file box and it reappeared.  But if I unchecked it one more time, it once again disappeared.  Weird stuff, but we are talking Intuit so nothing is ever weird enough to be shocking.